DNA: The Chemical Nature of the Gene Chapter 10

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DNA The Chemical Nature of the GeneChapter 10
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Chapter 10 Lecture Outline

• Historical perspective
• DNA structure
• RNA structure

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Early historical perspective
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We enter the 20th century with an understanding
of the DNA building block.
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Some Experimental Data leading to DNA as
biological source of DNA

• Griffiths
• Avery et al.
• Hershey and Chase
• Chargaff
• Wilkins and Franklin
• Watson and Crick

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Streptococcus pneumonia
Rough Strain
Smooth Strain
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Griffiths Experiment 1928
Conclusion A Transformation factor exists
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1944 AveryMacLeodMcMarty

• Discovered tranforming principle as DNA

Oswald Avery
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Avery, MacLeod McCarty
IIIS virulent bacteria
Heat killed homogenize and filter
Destroy either RNA protein or DNA
Add samples to non-virulent bacteria
Only bacteria without IIIS DNA did not transform
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August 20, 2003
Martha Chase dies With Alfred D. Hershey, she
established DNA as the genetic material By
Milly Dawson
1908 1997
1930-2003
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Hershey and Chase Experiment, 1952 Confirms DNA
as genetic material
Support for nucleic acid transfer
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Conclusion DNA identified as source of genetic
information
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At the same time amore detailed chemical
Structure of DNA was also ongoing
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Franklin and Wilkins 1947
1916-2004
1920-1958
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Chargaffs Rule 1948
1905-2002
1905-2002
1905-2002
1905-2002
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Watson and Crick, 1953 inferred the DNA structure
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Nobel Prize 1962
1928-
1916-2004
1916-2004
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Fraenkel-Conrat 1956RNA also carries genetic
information
VIRAL RNA
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Tobacco Mosaic Virus
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The Structure of Genetic Material
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The building blocks of DNA are nucleotides.
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RNAs Sugar DNAs Sugar
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Nitrogenous Bases
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DNA nucleotides
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Polarity and Anti-Parallel
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Back to Franklin and Wilkins Data Pairing of
specific classes of bases can account for
diameter of DNA
6 sided ring
6 sided ring 5 sided ring
Just right!
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Most Common Secondary Structure (3D structure)

• B-DNA
• Alpha Helix
• Right Handed Turn
• 10 bases per 360º turn

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A function of Major and Minor Grooves
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DNA
Special structures
Modifications

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Integration of DNA and RNA
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Information Transfer
Central Dogma
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